Dual functional catalyst of packing type and the catalytic distillation equipment

ABSTRACT

The present invention relates to a dual functional catalyst having both the catalytic reaction function and fractionation function and a catalytic distillation equipment for packing the catalyst therein. Said catalyst has a special shape and can be packed at random into the reaction section of said equipment. So, there exist adequate free spaces inside pellet and between pellets, enabling the vapor and liquid streams to pass through the catalyst beds directly and countercurrently, and contact with the dual functional catalyst directly. The reaction between the reactants and fractionation of products can be carried out simultaneously. Thus a high reaction efficiency is achieved. No special inner part is needed in the reaction section to pack the catalysts, so the structure of the equipment is simple and easy to operate, and the investment and cost of operation are low.

FIELD OF THE INVENTION

This invention relates to a dual functional catalyst having not onlycatalytic reaction function, but also fractionation function, and thecatalytic distillation equipment for packing said catalyst therein.

BACKGROUND OF THE INVENTION

The catalytic distillation technique is to carry out reaction ofreactants and separation of products in the same catalytic distillationapparatus, while the reaction(s) is being carried out, the formedproduct is separated out simultaneously, thereby the reactionequilibrium will be broken through continuously, making the reactiontoward completion and increasing the conversion of reactants.Furthermore, as the reaction heat is absorbed by vaporizing some of thecomponents, not only the reaction temperature will be kept constant andthe energy consumption of the process reduced significantly, but alsothe technological process will be simplified and the investment reducedgreatly. Generally, the catalytic distillation column consists of threesections: a rectification section at the upper part, a catalyticreaction section at the middle part and a stripping section at the lowerpart of the column. In the catalytic distillation column, the downwardflowing liquid stream and upward flowing vapor stream must flowcountercurrently through the catalytic reaction section at the middlepart to carry out reaction of reactants and fractionation of productssimultaneously therein. However, the particle size of conventionalcatalysts is too small, the flow resistance in the catalyst beds will beeven so high as to make the downward flowing liquid and the upwardflowing vapor streams difficult to pass countercurrently through thereaction section at the middle part of the column, and consequently makethe equipment impossible to run normally and the reaction of reactantsand fractionation of products impossible to be carried outsimultaneously.

In order to solve the problems aforesaid, some catalytic distillationequipments or methods for packing catalyst have been reported inliteratures. For example, U.S. Pat. No. 4,471,154 proposes to usecatalyst packed in capsules, made of fabrics or stainless-steel meshwhich are permeable to liquid but impermeable to catalyst particles,then these capsules are disposed on fractionating trays in the reactionsection at the middle part of the column to have the reactants diffusinginto the capsules, contacting with the catalyst and taking part inreaction when they flow across the trays. But the catalyst inventory ofthis structure is limited. U.S. Pat. No. 4,215,011 discloses a method ofwith catalyst packed in a number of bags, and the catalyst bags areplaced in said reaction section at the middle part of the column, havingcertain gap between the bags to allow liquid and vapor streams to passcountercurrently through said reaction section. U.S. Pat. No. 3,579,309discloses a structure wherein a number of small reactors are arrangedoutside the column, liquid stream flows from an upper tray through thesmall reactor outside the column and then back into next tray. Thus thestructure is complicated and the flow resistance of fluid is still high.In U.S. Pat. No. 3,634,534, the catalyst is placed in downcorners of thetrays, the inventory of catalyst is limited significantly. Besides,there are also other similar structures, but some of them are eithercomplicated structures, or in some others the amount of catalyst islimited, or in some the reacion efficiency is influenced due to the useof catalyst packed in small fabric capsules, thus not only the reactantshave to diffuse into the small capsules to contact with catalyst andundergo reaction, but also the products have to diffuse out therefromafter reacting.

U.S. Pat. No. 5,523,061 discloses a structure in which the catalyst ispacked into a number of overlapping-arranged fixed beds, between twoadjacent beds conventional trays is disposed, thus, only the liquidstream can pass through the catalyst bed and undergo reaction, and themass transfer and heat exchange can carry out on the trays between thevapor stream passing through the vapor channel and the liquid streamcoming from the upper catalyst bed. Since the vapor stream can notcontact with the catalyst directly, the reaction efficiency is affected.In the invention of CN 1065412A, the catalyst is placed between ripplepackings, the structure is complicated.

It is proposed in U.S. Pat. No. 4,250,052 that the packing typesulphonated resin catalyst with an inert skeleton is prepared bydissolving, at first, a vinyl aromatic polymer or copolymer in asolvent, coating the substrate of conventional distillation packing withthe resulting solution, then sulphonating the coated packing. However,the content of active component in the catalyst prepared by this processis low, and also the apparatus utilization coefficient is low;especially, the problems such as stripping and peeling off the activecomponents from the substrate and so on are resulted owing to differentrates of expansion, swelling and shrinkage between the substrate andactive components, and changes of other environmental factors such astemperature and medium and the like. In U.S. Pat. No. 4,194,964, it isdescribed only that the catalyst can be made into conventional shapes ofpacking, for instance, Raschig rings, Pall ring and rectangular saddleshape and the like, but not any method of preparation is described,moreover, the external surface area of the Raschig rings is small,separation efficiency and reaction efficiency are low, and its strengthis also weak; it is difficult to mould the catalyst materials into othershapes. U.S. Pat. No. 5,235,102 proposes that the catalyst is preparedas beehive-shaped regular packing having 1000 cells, preferably 100˜200cells per square inch. But the flow resistance over this catalyst ishigh because of its small pore channel; furthermore, it requires that aworker should enter the column to arrange this regular shaped packingone by one, manually, in a vertical position, and that the deactivatedcatalyst packing should be removed in the same way; such operation isarduous, and the residual organic material in the column is harmful tohuman body. The disclosure of CN 1060228A is mainly that the activecomponents of catalyst are made into a tray, but in doing so there aregreat difficulties technologically, besides the catalytic surface areacontacting with the reaction stream is very limited. The patent alsoproposes to make the catalyst into Raschig rings, vehicle wheel shape,Pall rings, rectangular saddles, spherical or cylindrical shapes, or theregular packings of ripple shape or beehive shape. However, the Raschigrings, which have low external surface area and weak strength, areunfavourable to the reaction and fractionation; wheel shaped catalysthas low external surface area and low allowable flow flux of vapor andliquid; Pall rings and rectangular saddle shape are difficult to bemoulded directly with the catalyst materials; the spherical andcylindrical catalysts have too small free space formed in the beds andhigher flow resistance to allow the vapor and liquid stream passingcountercurrently through the reaction section; as for said ripple orbeehive shaped regular packings, they also need to be loaded andunloaded manually in the column, and they are also difficult to be madewith the catalyst materials directly. GB2193907 discloses a hollowcatalyst with external ribs characterized in that the external ribs arearranged to avoid the adjacent catalyst pellets interlocking each other,for use in tubular reactor for conducting gas phase reaction such as thesteam conversion and oxidation in order to improve the distribution offluid and reduce the pressure drop. Even though it is used as a dualfunction catalyst in the catalytic distillation, the hollow shapedcatalyst is unfavourable for increasing the efficiency of reaction andfractionation owing to its small external surface area.

OBJECT OF THE INVENTION

An object of this invention is to develop a dual functional packing-typecatalyst having special shapes and the catalytic distillation equipmentfor packing said catalyst therein in order to overcome the deficienciesin the prior art.

The special shapes of catalysts of the invention are designed toincrease the counter current flow flux of vapor and liquid streams.

The catalytic distillation technique of the present invention is devisedto make the active substance of the catalyst or the catalyst carrierinto one having large external surface area and high strength, capableof being moulded into a given shape easily, and when packed at randominto the catalytic reaction section of the catalytic distillationcolumn, there will be adequate voidage inside the catalyst pellets andtherebetween to meet the requirement for countercurrent flow of bothvapor and liquid phases; the content of the catalyst materials in unitvolume is high as the whole catalyst pellet is made of the catalystmaterials, so the utilization ratio of the reaction section of theapparatus will be higher.

SUMMARY OF THE INVENTION

The invention relates to dual functional catalysts in given shapes whichhave both catalytic reaction function and fractionation function, and anovel catalytic distillation equipment packed with said catalyst. Thecatalysts of the present invention are made into special shape ofpacking for fractionation, which can be loaded directly into thereaction section at the middle part of the catalytic distillationcolumn. Said catalyst of the invention comprises enough free spacesinside the catalyst pellet and between the catalyst pellets to enable itto catalyze the reaction and separate the products simultaneously whenvapor and liquid streams passing countercurrently through the catalystbeds in the reaction section. As the catalyst has large external surfacearea and high strength, and both the vapor and liquid phase reactionmaterials can contact directly with the catalyst, the efficiency ofreaction and fractionation is increased, and moreover, the proportion ofthe catalyst material is high in per unit volume of the bed, this isalso favourable for increasing reaction efficiency. Because the catalystcan be easily loaded into the apparatus and no other specific structuralparts are required, the structure of the apparatus can be simplified,the investment reduced, and the operation also simplified.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an illustrative scheme of the structure of the catalyticdistillation column according to the present invention.

FIG. 2 shows illustratively the cross section of the window-latticeshaped catalyst with external teeth.

FIG. 3 shows illustratively the cross section of the star-shapedcatalyst with inner spokes.

CHARACTERISTICS OF THE INVENTION AND COMPARISON WITH THE PRIOR ART

There are two types of catalyst of the present invention in specialshapes:

1. A window-lattice shaped catalyst with external teeth having moderatefree space inside pellet and between pellets, suitable for use in thecatalytic distillation equipment of normal flow flux. 2. The star-shapedcatalyst with inner spokes having large free spaces inside and betweenthe pellets, for use in the catalytic distillation equipment whichrequires high flow flux.

Both the aforesaid two shapes of the dual functional catalyst can beloaded at random directly through the catalyst inlet into the reactionsection of the catalytic distillation equipment, and the useddeactivated catalyst can also be unloaded directly from the catalystoutlet without having worker enter the column to load and unloadcatalyst, thus preventing human body from any harm in the residues inthe column, and it is convenient to operate and low in operation cost.But in the prior art the catalyst made into regular packings in rippleor beehive shape, requires that the fresh catalyst must be placed one byone manually in the column, and the deactivated catalyst also must beremoved in the same manner, such operation is not only consumptive intime, labour and cost, but also harmful to workers who may be poisonedby the residue materials when working for a long period inside thecolumn.

As viewed from the content of catalyst materials, both the speciallyshaped catalysts of the invention are prepared and moulded by using thecatalyst material itself and a small amount of auxiliary agent, thepreparation methods are simple and the catalyst per se has enoughstrength required; as to the prior art using the method of coating theskeleton of packing type with the catalyst materials, the catalystmaterial coating is only a small portion of the whole catalyst pellet,so the content of catalyst material is low based on unit volume of thecatalyst bed in the reaction section, there is less chance of contactbetween reaction material and catalyst, and thus it is low in reactionefficiency.

As viewed from the external surface of catalyst, the external surfacearea of the two shapes of catalyst according to the invention is largerthan that of the catalyst of Raschig rings, the vehicle wheel shape andthe hollow shape with external ribs and so on, so there is more chanceof contact between reaction material and catalyst, and higher reactionefficiency, which are also favourable for the mass transfer and heatexchange between the materials both in vapor and liquid phases on thecatalyst surface and thereby the fractionation efficiency is increased.

As viewed from the free space formed inside pellet and between pelletsof catalysts, the voidage of the bed in reaction section formedrespectively by the two shapes of catalyst of the present invention, ishigher than that formed by the spherical, cylindrical, or vehicle wheelshape of catalyst and the like, and so the flow flux of the two phasestreams of vapor and liquid is also higher.

With respect to the moulding of catalyst, the special shapes of thecatalyst according to the invention can be obtained by extruding orpressing directly, but Pall rings, rectangular saddles and ripple orbeehive regular packings are not easy, or are very difficult, to bemoulded directly with catalyst materials.

To sum up, the dual functional catalyst in special shapes of theinvention has large external surface area, high content of catalystmaterial per unit volume of bed, and high reaction and fractionationefficiency. It is easy to mould, simple and convenient to produce, andhandy to operate. The catalyst can be directly loaded and unloadedthrough inlet and outlet without manual work inside column, preventinghuman body from harmful toxic matters. The free spaces formed in thebeds are large for both vapor and liquid phase streams passingcountercurrently through, the catalyst can be packed directly at randominto the reaction section without special loading structure, and theflow flux of the vapor and liquid is great.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a catalyst, which can be loaded at randomdirectly into the catalytic distillation column and related catalyticdistillation equipment, wherein said catalyst is a dual functional onehaving not only catalytic activity, but also fractionation function; thereaction material can react directly on the catalyst surface to achievehigh efficiency of reaction and fractionation; and the catalyst iseasily loaded and unloaded and the structure of the reaction section issimple.

A main technical feature of the present invention lies in that the dualfunctional catalyst developed in the invention has large externalsurface area, high reaction activity and adequate free spaces inside thecatalyst pellet and between the catalyst pellets; the catalyst can beloaded directly into the catalytic reaction section, in which the upwardflowing vapor stream and the downward flowing liquid stream can passcountercurrently through the reaction section and contact directly withthe catalyst and carrying out reaction and fractionation.

The catalyst pellet according to the invention has an equivalentdiameter of 6 mm-100 mm, preferably 15 mm-60 mm. Its height to diameterratio is 0.2-3:1, preferably 0.5-2:1. The cross section of the catalystmay be one of the two shapes shown in the FIG. 2 and FIG. 3. FIG. 2shows a window-lattice shaped catalyst with external teeth, which haslarge external surface area favourable not only for carrying outreaction, but also increasing the efficiency of fractionation, and ischaracterized in that the distance "b" between two opposite sides ineach cell is within the range of 2-8 mm, the thickness of the rib "a" iswithin the range of 1-6 mm, the height of each catalyst pellet is withinthe range of 10-100 mm, preferably 15-60 mm. The catalyst pellets areloaded at random in the reaction section at middle part of the catalyticdistillation column to allow the vapor and liquid stream to passcountercurrenly through the pore channel inside catalyst and the voidbetween catalyst pellets, not necessary to be placed in a verticalposition. FIG. 3 shows a star-shaped catalyst with inner spokes, whichhas relatively large free space inside the pellet, is suitable for usein the catalytic distillation column allowing relatively high flow fluxof fluid and relatively high reaction and fractionation efficiency, andis characterized in that the number of spokes is 2-20, preferably 4-10,the thickness of the rib "a" is within the range of 1-6 mm. The bodyform of the catalyst pellet may be cylindrical, elliptical, ormultilateral and other similar shapes.

The catalyst pellets in any one of the shapes shown in FIGS. 2 and 3, orthe mixture thereof, can be loaded at random into the reaction sectionof the catalytic distillation column, the free space formed between thecatalyst pellets occupies a volume of 20-60%, preferably 30-60%, of thetotal volume of the catalyst beds, the free space formed by the porechannel inside the catalyst pellet occupies a volume of 20-70%,preferably from about 30-60%, of the total volume of catalyst pellet.Thus, the reaction section formed in the catalytic distillation columnenables the upward flowing vapor stream and the downward flowing liquidstream to pass countercurrently through the reaction section contactingdirectly with the external surface of the catalyst as well the internalsurface of pore channel inside catalyst, and carrying out reaction andmass and heat transfer. The capacity of vapor and liquid flow fluxpermitted by the free spaces formed inside the catalyst pellet andbetween the catalyst pellets according to the invention is correspondingwith that permitted by the conventional trays and packings.

FIG. 1 shows a schematic diagram of the structure of the catalyticdistillation column, wherein the column 1 comprises a rectificationsection 2 at the upper part, a reaction section 3 at the middle part,and a stripping section 4 at the lower part. The supporting-plate 5 inthe reaction section at the middle part is loaded with the dualfunctional catalyst 6 of the invention; when the amount of the catalystheld-on is greater, the catalyst in the reaction section can be dividedinto several layers of catalyst beds. In the column, the upward flowingvapor stream and the downward flowing liquid stream will passcountercurrently through the catalyst beds of said reaction section,contacting directly with the catalyst and carrying out reaction andfractionation. In the rectification section at the upper part and thestripping section at the lower part, conventional fractionation trays orpackings can be used. The catalyst beds may be provided with thesupporting-plate 5, catalyst inlet 7 and outlet 8 for loading orunloading the catalyst directly, thus when the fresh catalyst is loadedand the deactivated catalyst is unloaded, the work can be doneconveniently and needs not to have an operator enter the column.Feedstock 13 is fed into the column from the reaction section orrectification section, or stripping section, and the liquid stream fromthe lowermost tray or packing layer of the rectification section flowsdownward and passes through the catalyst beds 9 in the reaction section;the vapor stream from the uppermost tray or packing layer of thestripping section flows upward and passes through the catalyst bed 9 ofthe reaction section, wherein the reaction and fractionation between theliquid and vapor streams take place simultaneously by the action of thedual functional catalyst 6 in the catalyst beds 9 until the reaction iscompleted or the desired conversion is achieved. After reaction, theupward flowing vapor stream flows out from the top of the column and iscooled and condensed in a condenser 10, a part of the condensate returnsback to the top of the catalytic rectification column as reflux, and theother part flows out of the unit as a low-boiling product 11. Thedownward flowing liquid stream, after reaction, flows out of the unitfrom the bottom, then a part of the liquid stream is vaporized viareboiler 14 and returns to the bottom of the unit, and the other part isdischarged out of the unit as a high-boiling product 12. If there is noquality norms or no critical quality control of the product from the topof the unit, the rectification section may not be equipped. The amountof catalyst in the reaction section and the number of the catalyst bedsdepend upon the reaction conversion desired. The shape and size of thecatalyst pellet may be selected according to the flow flux of the vaporstream and liquid stream flowing countercurrently in the reactionsection.

The dual functional catalyst of the invention can be prepared withactive components and a small amount of binder, for example, thesulphonic resin catalyst, metal oxide superacid catalyst and molecularsieve catalyst for hydration, etherification, esterification, ethercleavage and other reactions which can be catalyzed by acidic catalyst;and molecular sieve catalysts for isomerization and alkylation; and alsoa dual functional catalyst can be prepared by making metal oxides orother similar materials into a carrier which is then impregnated withthe active components necessary for different reactions. For example,hydrogenation and dehydrogenation catalysts can be prepared byimpregnating or spraying the active components of Groups VI or VIIImetals on a metal oxide carrier, e.g. alumina, which is suitable forhydrogenation and dehydrogenation reactons; and also an oxidationcatalyst can be prepared with heteropoly acid and the oxides of vanadiumfor the oxidation reaction etc.

For example, a dual functional sulphonic acid resin catalyst in any oneof the shapes as shown in the FIG. 2 and FIG. 3 may be prepared bysulphonating a copolymer of styrene and divinylbenzene with 98% sulfuricacid, preferably fuming sulfuric acid, then adding a binder and shapingin a moulding machine; or may also be prepared by adding a binder to thecopolymer of styrene and divinylbenzene, and shaping the resultedmixture, then sulphonating the shaped matter with 98% sulfuric acid,preferably fuming sulfuric acid. This catalyst can be used for the acidcatalytic reaction mentioned above. Compared with the catalyst preparedby coating sulfonic acid resin onto a skeleton of metal or ceramics, thecontent of the active components per unit volume of bed is high and thereaction efficiency and the ultilization ratio of the apparatus are alsohigh. The problems can be avoided related with the catalytic materialpeeling off from the substrate and so on due to different swelling andshrinking ratios of the resin and the substrate during operation andstopwork.

Furthermore, for example, a feedstock, e.g. aluminium hydroxide, isslurried by adding nitric acid having concentration of 10-15% and anextruding-aids, then made into one of the shapes as shown in FIG. 2 andFIG. 3 in a moulding machine; the moulded product is dried first at atemperature of 100-200° C., preferably 105-115° C., for 0.5-3 h,preferably for 1-1.5 h, to remove surface water; then calcined at atemperature of 250-500° C., preferably 300-400° C., for 1-6 h,preferably for 2-5 h, to remove crystalline water, and further calcinedat a temperature of 800-1500° C., preferably 1200-1350° C., for 2-12 h,preferably for 4-10 h, to form an Al₂ O₃ carrier; the obtained carrieris then impregnated quantitatively with the Palladium salt e.g. PdCl₂solution (2-5 g/l, the concentration of the PdCl₂ solution depends uponthe pore volume of the catalyst); then the impregnated carrier isfiltered, dried at a temperature of 100-150° C., and decomposed andreduced at a temperature of 200-700° C., preferably 400-600° C., toobtain a dual functional Pd/Al₂ O₃ catalyst containing Pd 0.1-0.5%,preferably 0.2-0.4%, which is used for selective hydrogenation to removedienes and alkynes from C₂ -C₅ light hydrocarbon fraction or gasolinefrom steam cracking.

Also, for example, a feedstock, e.g. aluminium hydroxide, is moulded,dried, and then calcined at 400-800° C., preferably 500-600° C., for2-12 h, preferably 4-10 h, to form an Al₂ O₃ having one of the shapesshown in FIG. 2 and FIG. 3; then the resulting Al₂ O₃ is impregnatedwith a salt of metal selected from Group VI or VIII, then theimpregnated metal salt is decomposed at 300-600° C. Thus a dualfunctional catalyst can be obtained for hydrorefining petroleum fractionoils.

Also, for example, zirconium nitrate is used as a feedstock, colloidedby adjusting the pH value to 8-12, preferably 110-120° C., with aqueousNH₄ OH solution, and the resulting colloid is filtered, washed toneutrality; after dried at 100-200° C., preferably 110-120° C., thedried product is sulphonated with sulfuric acid of 0.1-3 mol/L,preferably 0.5-1 mol/L for 2-3 h, washed again with water to neutrality,then dried and activated at 200-600° C., preferably 300-450° C., thenafter a binder is added, the activated product is moulded into one ofthe shapes as shown in the FIG. 2 and FIG. 3., to obtain a dualfunctional solid superacid catalyst which is used for the acid catalyticreaction processes, such as etherification and ether cleavage andalkylation and the like.

Also, for example, a molecular sieve having a SiO₂ /Al₂ O₃ ratio of5-100, preferably 8-30 is used as a feedstock; after a binder is added,it is moulded into one of the shapes as shown in FIG. 2 and FIG. 3, toobtain a packing-type catalyst, which is then calcined at 300-900° C.,preferably 400-700° C. for 4-6 h, to obtain a dual functional molecularsieve catalyst which can be used for the reaction processes, such asetherification, ether cleavage and hydrocarbon isomerization and so on.

The advantages of the invention are in that: the catalyst according tothe invention has dual function of both catalysis and fractionation; theactivity of catalyst is high as the catalytic materials or carrier aremade into the special shapes which are easily to be moulded and thecontent of catalytic materials per unit volume of the bed is high; thereaction efficiency and fractionation efficiency are high because ofhigh external surface area of the catalyst; the strength of the catalystis high, therefore the catalyst can be loaded directly through the inletinto the catalyst beds of the catalytic distillation column and thedeactivated catalyst can also be discharged from the outlet withoutmanual operation inside the column; there is large free space insidepellet and between the pellets in the beds, enabling the liquid andvapor streams to flow directly and countercurrently through the catalystbeds, contacting directly with the dual functional catalyst andsimultaneously carrying out reaction and fractionation, so its reactionefficiency is high; and no specific inner parts for loading catalystsare required in the reaction section, thus contributing to simplestructure, reduced investment and low operation cost.

EXAMPLES

The following examples are carried out in a catalytic distillationcolumn with a diameter of 120 mm, in which the rectification section andstripping section are filled with θ-shaped stainless steel mesh-ringpackings of φ6×6 mm in size. In examples 1-4, the height filled with thepackings is 2 m and 3.2 m respectively in the two sections, and inexample 5, the height filled with the packings is 3.2 m and 4.0 mrespectively in the two sections; the height of the reaction section atthe middle part depends upon the requirement of the given reactionprocess.

Example 1

The copolymer formed by copolymerizing styrene and divinylbenzene with acrosslinking degree of 10-18%, after a binder was added, was extrudedinto a carrier of star shape with inner spokes, then the resultingextruded matter was sulphonated with 98% concentrated sulfuric acid, theexcess sulfuric acid was filtered out, and the filtered product waswashed with water to neutrality, the dual functional sulphonic acidresin catalyst of packing type was obtained; 6 liters of the dualfunctional sulfonic acid resin catalyst obtained aforesaid and 6 litersof sulphonic acid resin catalyst in the shape of Raschig rings preparedby the same method of the present invention as the comparative sampleswere packed separately into the reaction section at the middle part ofrespective catalytic distillation equipment of the present invention toproduce MTBE (methyl tert-butyl ether) via the reaction betweenisobutene of C₄ fraction and methanol. The results are listed in Table1:

                                      TABLE 1                                     __________________________________________________________________________    Results of Example 1 in comparison with CN 1060228 A                                                     Comparative patent                                                   The invention                                                                          CN 1060228 A                                                         star shape with inner                                                                  Example 1                                                                              Comparative test                          Catalyst          spokes   reporter value                                                                         value Raschig rings                       __________________________________________________________________________    Outer diameter, mm                                                                              20       10       20                                        Internal diameter, mm                                                                           14       7        14                                        Height of pellet, mm                                                                            20       10       20                                        Thickness of ring wall, mm                                                                      3                 3                                         Thickness of rib, mm                                                                            2.5                                                         Height of the external tooth, mm                                                                2                                                           Exchanged equivalent, meg H*/g                                                                  4.2      --       4.2                                       Average pore diameter, nm                                                                       25       --       25                                        Specific surface area, m.sup.2 /g                                                               38       --       38                                        Average side pressure strength, Kg/pellet                                                       8.5      --       2.4                                       Reaction conditions and results:                                              Reaction pressure, MPa                                                                          0.65     0.6˜1.0                                                                          0.65                                      Reaction temperature, ° C.                                                               60˜65                                                                            40˜100                                                                           60˜65                               Ratio of methanol to isobutylene, mol/mol                                                       1.05     given ratio                                                                            1.05                                      Reflux ratio, Vol/Vol                                                                           1.0      --       1.0                                       Inventory of catalyst, L                                                                        6.0      --       6.0                                       Space velocity, h.sup.-1                                                                        3.0               3.0                                       Purity of MTBE, % 99.1              98.35                                     Average conversion, wt %                                                                        99.85    94.75    97.62                                     __________________________________________________________________________

Example 2

6 liters of the dual functional catalyst obtained from the example 1 foretherification were packed into the catalytic distillation equipment ofthe present invention, to carry out the reaction between tert-amylenesof FCC C₃ fraction and methanol to form TAME(tert-amyl methyl ether).The results obtained are listed in Table 2:

                  TABLE 2                                                         ______________________________________                                        Results of Example 2                                                                               Sulfonic acid resin catalyst                             Catalyst             same as that of example 1                                ______________________________________                                        Reaction conditions and results:                                              Reaction pressure, Mpa                                                                             0.45                                                     Reaction temperature, ° C.                                                                  65 ˜ 75                                            Ratio of methanol to tert-amylenes, mol/mol                                                        1.15                                                     Reflux ratio, vol/vol                                                                              1                                                        Amount of catalyst, L                                                                              6                                                        Space velocity, h.sup.-1                                                                           1.5                                                      Purity of TAME, %    98.0                                                     Tert-amylene conversion, wt %                                                                      92.7                                                     ______________________________________                                    

Example 3

Zirconium nitrate of 40 g/L concentration as feedstock was colloided byadjusting the pH value to 9.0-9.5 with NH₄ OH solution, then filtered,washed to neutrality with water, and dried at 110° C., then the driedproduct was sulphonated with sulfuric acid of 0.8 mol/L for 5 h,filtered, washed with water to neutrality, and after a binder was addedthe resulting product was moulded, the moulded matter was dried, andcalcined at 500° C. for 5 h, to obtain a solid superacid catalyst ofwhich the cross section was in the window-lattice shape with externalteeth. 8 Liters of the dual functional solid superacid catalyst obtainedby the process mentioned above were packed into the reaction section atthe middle part of the catalytic distillation equipment of the presentinvention to carry out decomposition of MTBE to produce ibsobutene. Theresults of the test listed in Table 3:

                  TABLE 3                                                         ______________________________________                                        Results of Example 3                                                                                The invention                                                                 a 9-cell window-                                                              lattice shape                                           Catalyst              external teeth                                          ______________________________________                                        Outer diameter, mm    20                                                      Thickness of ring wall, mm                                                                          2.5                                                     Thickness of spoke, mm                                                                              2.0                                                     Height of pellet, mm  20                                                      Acid strength, Ho     -12.7                                                   Specific surface area, m.sup.2 /g                                                                   42.5                                                    Average side pressure strength, Kg/ pellet                                                          3.6                                                     Reaction conditions and results:                                              Reaction temperature, ° C.                                                                   165                                                     Reaction pressure, MPa                                                                              0.7                                                     Space velocity, h.sup.-1                                                                            3.5                                                     Reflux ratio, vol/vol 1:1                                                     Decomposition conversion of MTBE, %                                                                 98.5                                                    Selectivity to isobutene, %                                                                         95.6                                                    ______________________________________                                    

Example 4

After 25 wt % of a binder was added, the USY molecular sieve having aSiO₂ /Al₂ O₃ ratio of 13 was kneaded homogeneously and extruded intoStar shape with inner spokes, then calcined at 600° C. for 4 h, a dualfunctional molecular sieve catalyst was obtained. 5 Liters of the dualfunctional molecular sieve catalyst prepared by the process mentionedabove were packed into the reaction section at the middle part to carryout the alkylation reaction of benzene and ethylene, the results arelisted in Table 4:

                  TABLE 4                                                         ______________________________________                                        Results of Example 4                                                                                a 9-cell star shape                                                           with spokes                                             ______________________________________                                        Outer diameter, mm      20                                                    Thickness of ring wall, mm                                                                            2.5                                                   Thickness of spoke, mm  2.0                                                   Height of pellet, mm    20                                                    Specific surface area, m.sup.2 /g                                                                     620                                                   Average side pressure strength, Kg/ pellet                                                            4.5                                                   Reaction conditions and results                                               Reaction temperature, ° C.                                                                     210                                                   Reaction pressure, MPa  3.6                                                   Reflux ratio, vol/vol   all refluxed                                          Space velocity, h.sup.-1                                                                              1.5                                                   Ratio of ethylene to benzene made-up, mol/mol                                                         1:1                                                   Conversion of ethylene, wt %                                                                          ˜100                                            Selectivity to Ethylbenzene, %                                                                        88.6                                                  ______________________________________                                    

Example 5

Aluminium hydroxide with a sodium content less than 0.1% was used as afeedstock, and was slurried by adding 4% of a 10% HNO₃ solution; the 5%sesban powder is used as an extruding aids; the resulting paste waskneaded then extruded in a moulding machine into a carrier having across section in window-lattice shape with external teeth; then thecarrier was dried at first at 110° C. for 1-1.5 h, calcined at 300-400°C. for 2-2.5 h to remove crystalline water, calcined again at 1200-1300°C. for 4-8 h to form a Al₂ O₃ carrier; then the Al₂ O₃ a carrier wasimpregrated with a 3 g/l PdCl₂ solution to give a Pd content of0.25-0.30% on it; The obtained matter is then reduced in the presence ofhydrogen at 70-100° C., to obtain a dual functional Pd/Al₂ O₃ catalystfor selective hydrogenation to remove diene and acetylenes. 2 Liters ofthe catalyst obtained according to the invention and 2 liters of thecatalyst of Raschig ring shape prepared by the same process of theinvention were packed separately into the reaction section at the middlepart of respective catalystic distillation equipment of the presentinvention to carry out selective hydrogenation of allene and propyne inC₃ +C₄ mixture fraction from the steam cracking. The feedstock comprises64.83% of propylene, 1.14% of propane, 2.25% of allene+propyne and31.78% of C₄ Compounds. The test results are listed in Table 5:

                  TABLE 5                                                         ______________________________________                                        Results of Example 5                                                                           Present invention                                                             Window-lattice                                                                             Comparative                                                      shape with 9 cells                                                                         Raschig                                         Catalyst         and external teeth                                                                         rings                                           ______________________________________                                        Palladium content, %                                                                           0.24         0.24                                            Outer diameter, mm                                                                             20           20                                              Internal diameter, mm                                                                          15           15                                              Thickness of ring wall, mm                                                                     2.5          2.5                                             Thickness of spoke, mm                                                                         2.0          --                                              Height of pellet, mm                                                                           20           20                                              Average pore diameter, nm                                                                      210          240                                             Specific surface area, m.sup.2 /g                                                              25           25                                              Average side pressure strength,                                                                15           4.3                                             Kg/pellet                                                                     Reaction pressure, MPa                                                                         1.8          1.8                                             Reaction temperature, ° C.                                                              30 ˜ 45                                                                              30 ˜ 45                                   Mole ratio of hydrogen to diene                                                                1.5          1.5                                             and alkyne, mol/mol                                                           Reflux ratio     1.0          1.0                                             Residue of allene and propyne in                                                               <10          <10                                             overhead fraction, ppm                                                        Yield of propylene, %                                                                          103.6        103.4                                           Content of C.sub.4 in overhead                                                                 0.43         0.81                                            fraction, %                                                                   ______________________________________                                    

What is claimed is:
 1. A dual functional catalyst, comprisingcylindrical pellets which are moulded such that a cross-section of eachpellet has a window-lattice shape with external teeth or a star shapewith inner spokes, wherein in said window-lattice shape, the distancebetween two opposite sides in each cell is within the range of 2-8 mm,the thickness of the rib is within the range of 1-6 mm, and wherein insaid star shape with inner spokes, the number of spokes is 2-20, thethickness of the rib is within the range of 1-6 mm, and wherein thecatalyst is simultaneously and efficiently capable of performingcatalysis and fractionation functions when it is directly and randomlyloaded into a reaction section of catalytic distillation equipment. 2.The dual functional catalyst according to claim 1, wherein each pelletis from 6 to 100 mm in diameter and the ratio of height to diameter ofeach pellet is from 0.2 to
 3. 3. The dual functional catalyst accordingto claim 2, wherein the ratio of height to diameter of the pellet isfrom about 0.5 to
 2. 4. The dual functional catalyst according to claim1, wherein the free space inside each pellet occupies from 20% to 70% ofthe pellet volume.
 5. The dual functional catalyst according to claim 4,wherein the free space inside each pellet occupies from 30% to 60% ofthe pellet volume.
 6. The dual functional catalyst according to claim 1,wherein the catalyst is prepared by sulfonating the powder of copolymerof styrene and divinylbenzene with concentrated sulfuric acid, adding abinder to the sulfonated powder, and then moulding the resulting blendinto shape in a moulding machine.
 7. The dual functional catalystaccording to claim 1, wherein the catalyst is prepared by adding abinder to the powder of copolymer of styrene and divinylbenzene,moulding the resulting blend into shape in a moulding machine, and thensulfonating the moulded matter with concentrated sulfuric acid, toobtain the catalyst.
 8. The dual functional catalyst according to claim1, wherein the catalyst is prepared by using aluminum hydroxide as afeedstock, moulding the feedstock into shape, calcining the mouldedmatter at from 800 to 1500° C. to form an alumina carrier, thenimpregnating the resulting carrier with the solution of a palladiumsalt, and drying the impregnated carrier, then forming a Pd--Al₂ O₃catalyst containing from 0.01 to 1.0% Pd by decomposing and reducing thedried product.
 9. The dual functional catalyst according to claim 8,wherein the moulded matter is calcined at from 900 to 1300° C.
 10. Thedual functional catalyst according to claim 9, wherein the Pd--Al₂ O₃catalyst contains from 0.02 to 0.6% Pd.
 11. The dual functional catalystaccording to claim 1, wherein the catalyst is prepared by using aluminumhydroxide as a feedstock, moulding the feedstock into shape and dryingthe moulded matter, then calcining at from 300 to 900° C. to form analumina carrier, and impregnating the calcined carrier with a salt ofmetal selected from Groups VI and/or VIII, then decomposing andsulfiding the impregnated carrier at from 300 to 800° C. to obtain thecatalyst.
 12. The dual functional catalyst according to claim 11,wherein the moulded matter is calcined at from 400 to 600° C.
 13. Thedual functional catalyst according to claim 12, wherein the impregnatedcarrier is decomposed and sulfided at from 450 to 600° C.
 14. The dualfunctional catalyst according to claim 1, wherein the catalyst is asolid superacid catalyst prepared by using zirconium nitrate as afeedstock, precipitating the feedstock with aqueous ammonia of pH from 8to 12 washing the resulting precipitate with water to neutrality, dryingit at from 110 to 120° C.; sulfonating the dried precipitate withsulfuric acid of from 0.1 to 3.0 mol/L for a reaction time of from 2 to3 h, then washing it with water again to neutrality, drying, adding abinder to the dried product, moulding the product into shape, and thenactivating the moulded product at from 200 to 600° C.
 15. The dualfunctional catalyst according to claim 14, wherein the aqueous ammoniais of pH from 9 to
 10. 16. The dual functional catalyst according toclaim 15, wherein the sulfuric acid is of from 0.5 to 1 mol/L.
 17. Thedual functional catalyst according to claim 16, wherein the mouldedproduct is activated at from 300 to 450° C.
 18. The dual functionalcatalyst according to claim 1, wherein the catalyst is prepared bykneading a molecular sieve and a binder, moulding the resulting blendinto shape, then calcining the moulded matter at from 300 to 900° C. toobtain the catalyst.
 19. The dual functional catalyst according to claim18, wherein the moulded matter is calcined at from 400 to 700° C.